Abstract: The Chuxiong Basin is a Mesozoic foreland basin in central Yunnan.The sediments in the basin may fall into two subtypes:foreland flysch and foreland molasse.The former is represented by grey and/or dark grey thin-bedded organic-rich silty mudstone and muddy silt-stone associations as important source rocks intercalated with marls,while the latter consists of delta-littoral sandstones as hydrocarbon reservoirs.The basin is separated by the Yupaojiang-Sanjie thrust fault into two parts:the thrust nappe in the west and protobasin in the east.
The thrust nappe is assembled by root zone,major thrust zone and thrust front.The thrusting may be traced back to the Ladinian (Middle Triassic) and overthrusted toward the Yangtze craton,thus resulting in the formation of fault-bend trap,fault propagation trap,step thrust fault-stratigraphic trap,basement detachment trap and fault-fold trap in the subduction zone of the nappe front.It is clear that the thrust nappe is expected to be an important reservoir package.